Rolling mill apparatus and methods of rolling metal

ABSTRACT

The invention relates to a method of and apparatus for rolling metal wherein the metal is passed to and fro between the rolls of at least one pair of rolls and is gripped alternately by gripping members mounted at opposite sides of the roll pass. The metal is first gripped in a first gripping member mounted for reciprocating movement towards and away from one side of the rolls and is thus entered into the pass by movement of said gripping member towards the rolls. The metal is then received at the other side of the pass in a second gripping member mounted on that side of the pass for reciprocating movement towards or away from the rolls; the metal moves lengthwise in the direction of rolling relative to the second gripping member until free of the rolls. The metal is thereupon gripped in said second gripping member and is then reentered between the rolls (into the same or another pass) by movement of the second gripping member back towards the rolls and is again received at the first mentioned side of the rolls in the first gripping member.

United States Patent lnventor Alexander Ian Wilson Sheffield, EnglandApp]. No. 867,226 Filed Oct. 17, 1969 Patented Dec. 28, I971 AssigneeThe Hille Engineering Company Limited Sheffield, England Priority Oct.23, 1968 Great Britain 50,408/68 ROLLING MILL APPARATUS AND METHODS OFROLLING METAL 22 Claims, 5 Drawing Figs.

[52] US. Cl 72/222, 72/252 [51] Int. Cl B2lb 39/14 [50] Field of Search72/24, 252, 222, 227, 221, 250

[56] References Cited UNlTED STATES PATENTS 29,702 8/1860 Lauth 72/252276,086 4/1883 Shaffer 72/252 Primary Examiner-Milton S. MehrAnomeyErnest A. Greenside ABSTRACT: The invention relates to a method ofand apparatus for rolling metal wherein the metal is passed to and frobetween the rolls of at least one pair of rolls and is grippedalternately by gripping members mounted at opposite sides of the rollpass. The metal is first gripped in a first gripping member mounted forreciprocating movement towards and away from one side of the rolls andis thus entered into the pass by movement of said gripping membertowards the rolls. The metal is then received at the other side of thepass in a second gripping member mounted on that side of the pass forreciprocating movement towards or away from the rolls; the metal moveslengthwise in the direction of rolling relative to the second grippingmember until free of the rolls. The metal is thereupon gripped in saidsecond gripping member and is then reentered between the rolls (into thesame or another pass) by movement of the second gripping member backtowards the rolls and is again received at the first mentioned side ofthe rolls in the first gripping member.

PATENIED UEB28 um SHEET 1 BF 4 PATENTED UEB28 I97! SHEET 2 OF 4//\/l/E/\/ TOP Alexander Ian Wilson PATENTEDnEB28|97I 3630.061

SHEET U UF 4 Alexander Ian Wilson ROLLING MILL APPARATUS AND METHODS OFROLLING METAL This invention relates to rolling mill apparatus andmethods of rolling metal.

In the rolling of metal, material is fed into passes between rollseither manually or mechanically for reduction between the rolls. Manualfeeding is still used extensively, particularly for rolling specialsteels and where size changes are frequent; a heavy, hot and unpleasantjob involving a large labor force. Mechanical feeding in cases where thematerial leaves one pass before entering the next has involved the useof chute guides, deflector plates, cross transfer gear, skew tables,turnup devices etc., and size changing necessitates rearrangement of theguides, plates etc. which is extremely time consuming. Mechanicalfeeding in cases where the material enters a pass before leaving theprevious pass as in continuous mills also necessitates the use of alarge number of mill guides, guide troughs, repeaters etc., and accuratespeed control is generally essential, thus such mills become veryexpensive and inflexible and can only be economically operated on largetonnages of a similar size range.

The object of the present invention is to provide improvementsapplicable to rolling mill apparatus and to methods of rolling, at leastsome of which can in some measure reduce or overcome some of thedisadvantages outlined above.

According to one of its aspects the invention provides a method ofrolling metal in which a first end portion of the metal is gripped in afirst gripping member mounted for reciprocating movement towards andaway from one side of one or more passes between rolls and is enteredinto a pass by movement of the first gripping member towards the passfrom a rearward position, the first end portion is received at the otherside of the pass in a second gripping member mounted on that side forreciprocating movement towards or away from the pass or passes, themetal moves lengthwise in the direction of rolling relative to thegripping members until its other end portion is received in the secondgripping member, that other end portion is gripped in the secondgripping member and is entered into the same or another pass by movementof the second gripping member back towards that pass and is againreceived at the first mentioned side of that pass in the first grippingmember. The end portion of the material may be moved laterally by thegripping members by the action of fluid operated means when, prior tobeing entered into the bite of a pair of rolls having a plurality ofpasses spaced from each other, the material is aligned with the requiredone of said passes. The material may be rotated by the gripping membersby the action of fluid operated turning means, for example when dealingwith an oval section in course of reduction to round bar. In a preferredform of the invention, a first pair and a second pair of rolls rotate inopposite directions so that each is able to feed metal towards or awayfrom the pass of the other, at least one roll of the second pair isretracted to an inoperative position, the second gripping member ismoved to a forward position in the gap between the second pair of rollsand receives from or enters into the bite of the first pair of rolls anend portion of the metal, the second gripping member is moved to itsrearward position clear of the second pair of rolls, the retracted rollor the retracted rolls of the second pair is or are returned to theoperative position, at least one roll of the first pair is retracted toan inoperative position and the first gripping member is moved to itsforward position in the gap between the first pair of rolls to receivefrom or enter into the bite of the second pair the other end portion ofthe metal. Where the arrangement is such that the pass line between onepair of rolls is higher than the pass line between the other pair ofrolls, vertical adjustments of the gripping means may be effectedbetween successive rolling operations. While metal is passing throughthe pass of one pair of rolls, the position of a nonretractable roll ofthe other pair may be adjusted by screw means to determine the width ofthe roll gap of that other pair when its retractable roll has beenreturned to its operative position. Preferably the movement of thegripping members to their operative positions and the adjustment of thenonretractable rolls are all effected under the control of electricalprogramming means.

According to another of its aspects, the invention provides rolling millapparatus which includes at least two rolls mounted to form one or morepasses, a first gripping member and a second gripping member mounted onopposite sides of the pass or passes for reciprocating movement towardsand away therefrom, and clamping means for releasably clamping metal insaid gripping members alternately, the arrangement being such that eachgripping member is able in the course of its movement towards a pass toenter an end portion of metal into the pass and is subsequently able toreceive near the pass an end portion of metal travelling therefrom.Preferably each gripping member includes a tube for receiving the metal.Each clamping means preferably includes a lever able to bear withclamping action against the metal (when present). Preferably, eachclamping means also includes a fluid pressure operated piston andcylinder arrangement able to cause the lever to bear against the metal.The lever may be so shaped and i mounted that an elongate part of it canbear against the metalto constrain it against a corresponding length ofthe tube. A sensing device is preferably provided to sense entry of themetal into each gripping means and is operatively connected to cause thelever to be applied with light pressure against the a metal (whenpresent) to quickly decelerate the bar when the trailing end of the barhas passed between the rolls. The gripping means may however be providedwith a pair of pinch rolls for driving out a leading end of a bar whichthe clamping means have failed to arrest as the gripping means havereceived said material from a pass. The gripping members may be mountedupon carriages arranged for movement towards and away from the pass orpasses under the action of fluid pressure. Preferably the carriages arealso arranged for lateral movement. The gripping members may be mountedfor rotational movement about a longitudinal axis thereof. Desirably aload sensitive device is provided to sense when a pair of rolls ceasesto be under load consequent upon the metal having left that pair ofrolls and is operatively connected to cause the respective grippingmember to move away from the bite by a predetermined distance to arearward position. In a preferred embodiment of the invention, two pairsof rolls are mounted so that each pair is able to feed metal towards thebite of the other, and at least one roll of each pair is retractablefrom an operative position to an inoperative position, the arrangementbeing such that each gripping member is able when the retractable rollor rolls of a pair of rolls has been retracted to extend through the gapbetween those rolls to a forward position near the bite of the otherpair of rolls. Means may be provided for effecting vertical adjustmentsof the gripping means between successive rolling operations tocompensate for the pass line between one pair of rolls being higher thanthe pass line between the other pair of rolls. Abutments may be providedto determine the operative positions of the retractable rolls.Preferably a nonretractable roll of each pair has screw means associatedwith it able to determine the gap between the rolls when the retractableroll is in its operative position. Preferably electrical programmingmeans are operatively connected to control the retraction of theretractable rolls, the adjustment of the nonretractable rolls and themovement of the gripping members.

In order that the invention may be clearly understood and readilycarried into effect a preferred embodiment thereof will now bedescribed, by way of example only, with reference to the accompanyingdrawings in which:

FIG. I is a diagrammatic general arrangement drawing of rolling millapparatus;

FIG. 2 is a side elevation, partly in section, of roll stands andmanipulators forming part of the apparatus, as seen along the line IIIIof FIG. 3;

FIG. 3 is a top plan, partly in section as seen along the line lll-lllof FIG. 2;

FIG. 4 is a sectional view taken on the line IV--IV in FIG. 2,

and the retraction of the retractable rolls from and their return andFIG. 5 shows the roll stands in greater detail in part sectional sideelevation.

Turning to the drawings, there is shown rolling mill apparatus havingroll stands in housings l0 and 12, integral to form a double-duohousing. The housing carries a first pair of rolls 14 and 16. The lowerroll 14 is retractable by a hydraulic ram 18 from its operative position(see FIGS. 1 and 2) to an inoperative position shown in broken lines.The housing 12 carries a second pair of rolls 20 and 22. Here the upperroll 20 is retractable to an inoperative position from an operativeposition shown in broken lines. The retractable rolls l4 and 20 arecarried by chairs 24 (see FIG. 5) slidable in windows 25 of the housingsand their operative positions are determined by abutments in the form ofshoulders 26 against which the chairs are held by hydraulic pressurewhen the rolls are moved to their operative positions by the rams 18.The position of the nonretractable rolls 16 and 22 is adjustable byscrews 28 driven by electric motors 30 to vary the roll gap. (It will beseen that in this particular arrangement the pass line is not constant,but for each pair of rolls varies in accordance with the roll gapsetting. In addition, the pass line between the rolls 14 and 16 ishigher than the pass line between the rolls 20 and 22 to ensure adequateclearance of the nonretractable roll of the inoperative pair of rolls ateach pass). Load sensing devices 32 associated with each pair of rolls(FIG. 1) can signal when metal passing between the rolls has left thebite between them. A motor 33 is drivingly connected to the rolls. Therolls have conventional side-by-side box passes, oval passes and roundpasses for reducing metal bar.

Manipulators include a first gripping member generally designated 34disposed to one side namely to the left of the bite formed between thepair of rolls in the housing 10, and a second gripping member 36disposed to the right of the housing 12. Each gripping member includes atube 38 (see FIGS. 1 to 3), clamping means in the form of a lever 40, apneumatic piston and cylinder arrangement 42 for actuating the lever 40,a pneumatic ram 44 for imparting reciprocating movement to the tubetowards and away from the rolls, a hydraulic ram 46 for impartingtransverse movement to the tube, a pneumatically actuated turning device48 for imparting rotation to the tube and sensing means 50 to signal thearrival in the tube of metal from the adjoining rolls. Electricalprogramming means 52 is operatively connected to the several parts. Theleading end of the tube 38 can be brought to any one of 3 positions ofrest by the pneumatic ram 44, namely a rearward position indicated (a),a normal or intermediate position (b) and a forward position (c).

Turning more particularly to FIGS. 2 and 3, the tube 38 of each grippingmember has an outwardly flared nose 54 at its open end and an opening 56in its side. The lever 40 is mounted upon a pivot 58; it has an elongatepart 60 extending into the tube through the opening 56 and a stub part62 which can be acted upon by the pneumatic piston 42 (not shown inFIGS. 2 and 3) to urge elongate part 60 towards the inner side of thetube remote from the opening 56. The tube 38 is mounted on a carriage inthe form of a trolley 64. The pneumatic ram 44 is mounted on the trolleyto move the tube along a runway 66 towards and away from the bite of therolls. Hydraulic ram 46 is mounted to traverse the trolley along a track68 on which it is supported by a wheel 70 and along a guide 72, wherebythe tube 38 can be made to move transversely of the rolls. The tube 38is rotatably mounted in bearings 74 by way of bushes 76 and can berotated by the rotating device 48 comprising pneumatic ram 78 andlinkage 80.

Means including hydraulic cylinders 82 are provided for adjusting thevertical height of the leading end of each tube 38 between successiverolling operations to compensate for the pass line between rolls 14 and16 being higher than the pass line between rolls 20 and 22. Whenvertical adjustments are made, the gripping members and trolleys onwhich they are mounted move bodily about the points on the tracks 68where the wheels 70 are resting.

Operation of the apparatus while reducing metal bar at the stage ofrolling to oval sections is as follows. The leading end of the tube 38of the left hand gripping member 34 will initially be in its retractedposition (a) (not shown in the drawings) holding the right-hand endportion of a bar 82 with the end of the bar protruding forwardly and themain length of the bar trailing rearwardly. Retractable roll 14 inleft-hand housing 10 will be in its operative position andnonretractable roll 16 will be at a correct setting ready for rollingthe bar through a selected oval pass in the rolls. Retractable roll 20in the right-hand housing will be in its retracted position. The leadingend of the tube 38 of the right-hand gripping member 36 will be in itsforward position (i c) extending between the rolls of the right handhousing to near the bite of the left-hand housing. The tubes 38 willboth be in the transverse position corresponding to the selected passand will thus be both aligned with that pass and with each other. Lever40 of the left hand gripping member 34 will be actuated firmly to gripthe bar 82 and the lever of right-hand gripping member 36 will not beactuated so as to lie close to opening 56 through which it projects. Theleft hand gripping member will be oriented to present the bar with themajor axis of its oval section vertical and thus its lever 40 will bepressed against the bar from the side. The right-hand gripping memberwill be oriented to receive the bar with the major axis of its sectionhorizontal so that lever 40 can press against the bar from below (seeFIG. 2). The rolls are kept in constant rotation by motor 33 in oppositedirections so that each pair of rolls 14-16 and 20-22 can in turn feedthe bar in the direction of the other pair.

Programmer 52 delivers an electrical signal to actuate pneumatic ram 44of left-hand gripping member 34 which moves tube 38 to bring its leadingend to the normal position (b) (see FIG. 2) thereby entering theprotruding end of the bar into the selected pass between the left-handpair of rolls. Load sensing device 32 of the left-hand pair of rollsdelivers a signal to the programmer which in turn delivers a signal todeactivate pneumatic piston 40 of the left-hand gripping member torelease the bar. The end portion of the bar is reduced in the oval passand is received in the aligned tube 38 at the right-hand side of thebite, being guided by flared nose 54 of that tube. Sensing means 50detects the arrival of the bar in the tube, causing a signal to bedelivered by way of the programmer to its associated pneumatic piston 42to cause it to apply the lever with light pressure against the metal;the metal being constrained by the elongate part of the lever against acorresponding length at the side of the tube is thereby quicklydecelerated when the trailing end of the bar has passed between therolls 14, 16 and throw out" is eliminated or reduced. (If desired, apair of pinch rolls 39 may be provided some distance rearwardly of theleading end of each tube as shown in chaindotted lines in FIGS. 2 and 3,said rolls being drivable by means not shown and adjustable towards andaway from each other as indicated by the arrows in FIG. 3. If throwoutof material should occur, that is to say if the trailing end of thematerial should slip past the elongate part 60 of the lower 40 into thetube, the pinch rolls will then be used to drive it out again).

As rolling progresses, the programmer delivers a signal to the motor 30associated with the nonretractable roll of the right-hand housing toadjust its setting in readiness for the next rolling operation; sincethis adjustment takes place while the other pair is operative, theadjustment can be effected slowly and accurately without hold up of themill (e.g., by the use of a slow thread screw and slow moving motor).

When the whole length of the bar has been reduced in the selected pass,its left-hand end will have been drawn from the tube of the left-handgripping member so that the left-hand end portion is held in the tube ofthe right-hand gripping member and the load sensing device 32 of theleft-hand pair of rolls will have signalled to the programmer that thebar is no longer in the bite. Thereupon the programmer delivers signalsfor several steps to take place, namely for pneumatic piston 42 of theright-hand gripping member to cause its lever firmly to grip the bar,for pneumatic ram 44 to move the right-hand tube to the right from outof the gap between the right-hand rolls so that its leading end assumesthe rearward position (a), for the hydraulic rams 18 to retractleft-hand retractable roll 14 from its operative position and to moveright-hand retractable roll 20 to its operative position (and to hold itthere), for the hydraulic rams 46 to move the trolleys 64 transverselyinto alignment with the next selected pass (it is assumed that this isnot in alignment with the previous selected pass), for the pneumaticrams 78 to cause their respective turning devices 48 to be rotatedthrough 90 by way of their linkages 80, for the pneumatic ram 44 of theleft-hand gripping member to move its tube to its forward position (c),for the leading ends of the tubes to be vertically adjusted and,finally, for the pneumatic ram 44 of the right-hand gripping member tomove to its normal position (b) thereby entering the left-hand end ofthe bar into the bite between the righthand rolls for the process to berepeated.

The bar is rolled in the mill, being reversed to and fro, from end toend and from pass to pass until the reduction has been completed. Therolling program and the operation of the manipulators is whollyautomatic, being preset upon for example punched card fed into theprogrammer.

The apparatus described above has many advantages quite apart fromautomaticity. Some of the material is always contained in one or otherof the gripping members and is not at any time completely let loose. Theconstraint applied by the levers 40 during rolling assists inmaintaining the bar straight. The bar is afforded straight entry intothe rolls and supported run out from the rolls and does not requirelifting through large distances. Cross transfer is through comparativelysmall distances as one pair of rolls is directly behind the other andindeed in some reduction sequences cross transfer is at times avoidedaltogether where the pass in one pair of rolls for the forward journeyis in line with the pass in the other pair of rolls for the returnjourney. Different reduction sequences can be set up upon punched cardsand then it is possible for many applications to change the reductionsequence by the mere change of a punched card in the programming device.

it will be appreciated that many modifications can be made in theapparatus described above without departing from the scope of theinvention. For example the manipulators can be used with rolling millsof different configurations, for example with reversing two-high mills(where the gripping members will move only between their normal andtheir rearward positions), side-by-side two-high mills (where thegripping members will be traversed from one to the other betweenconsecutive passes), and three-high mills (where a device for liftingand lowering the gripping members bodily would have to be provided). Itwill in fact be preferable for both rolls of a twohigh mill, or for bothrolls of each stand of a double-duo arrangement, to be retractablesimultaneously and through equal distances so that the pass line is keptconstant, roll gap adjustments being made in any convenient manner. Inthis way it will be unnecessary for the gripping members to bevertically adjustable. It is envisaged that the gripping members will beused in conjunction with simplified feed forms of stripper and entryguide particularly for rolling comparatively thin or light materials.The manipulator movements and also the rolling program could becontrolled manually, in a semiautomatic mill, for example by operationof electrical controls from an adjoining desk. The load sensing devices32 could be replaced by photoelectric cells for giving an electricalsignal when the end of a length of material has passed through one orother of the pair of rolls.

What I claim and desire to secure by Letters Patent is:

l. A method of rolling metal, comprising gripping a first end portion ofthe metal for movement relative to a pass between rolls, entering thegripped metal into the pass by a first reciproeable gripping member forthe metal when the gripping member is moved toward the pass from arearward position, receiving the first end portion of the metal at theother side of the pass in a second gripping member mounted on said otherside for reciprocating movement towards and away from the pass, movingthe metal lengthwise in the direction of rolling relative to thegripping members until its other end portion is received in the secondgripping member, gripping said other end portion in the second grippingmember, and reentering said gripped other end portion between the rollsby movement of the second gripping member back towards the rolls forreception of said metal at the first mentioned side of the pass by thefirst gripping member.

2. The method according to claim 1, characterized by moving the endportion of the metal laterally by the gripping mem bers by the action offluid operated means, when, prior to being entered into the bite of apair of rolls having a plurality of passes spaced from each other, themetal is aligned with the required one of said passes.

3. The method according to claim 1, characterized by rotating thegripping members by the action of fluid operated turning means.

4. The method according to claim 1, characterized by rotating a firstpair and a second pair of rolls in opposite directions so that each isable to feed said metal towards and away from the pass of the other,retracting at least one roll of the second pair to an inoperativeposition, moving the second gripping member to a forward position in agap between the second pair of rolls and alternately receiving from andentering into the bite of the first pair of rolls an end portion of themetal, moving the second gripping member to its rearward position clearof the second pair of rolls, returning the retracted roll of the secondpair to its operative position, retracting at least one roll of thefirst pair to an inoperative position, and moving the first grippingmember to its forward position in the gap between the first pair ofrolls to alternately receive from and enter into the bite of the secondpair the other end portion of the metal.

5. The method according to claim 4, characterized by verticallyadjusting the gripping members between successive rolling operations tocompensate for the pass line between one pair of rolls being higher thanthe pass line between the other pair of rolls.

6. The method according to claim 4, characterized by adjusting, whilemetal is passing through the pass of one pair of rolls, the position ofa nonretractable roll of the other pair to determine the width of theroll gap of that other pair when its retractable roll has been returnedto its operative position.

7. The method according to claim 4, characterized by the movement of thegripping members and the retraction of the retractable rolls from andtheir return to their operative positions and the adjustment of thenonretractable rolls are all effected automatically.

8. Rolling mill apparatus including at least two rolls mounted to format least one pass, a first gripping member and a second gripping membermounted on opposite sides of the pass for reciprocating movement towardsand away therefrom, clamping means for each gripping member adapted toreleasably clamp metal in said gripping members alternately, and meansfor moving at least one of said gripping members independently of theother gripping member, said one of said gripping members being adaptedupon movement thereof to enter an end portion of metal into the pass andsubsequently to receive near the pass an end portion of metal travellingtherefrom.

9. Apparatus according to claim 8, wherein each gripping member includesa tube for receiving the metal.

10. Apparatus according to claim 8, wherein each clamping means alsoincludes includes a lever.

11. Apparatus according to claim 10, wherein each clamping means alsoincludes a fluid pressure operated piston and cylinder arrangement foroperating the lever.

12. Apparatus according to claim 10, wherein the lever has an elongatepart which bears against metal adapted to be gripped by the associatedgripping member to constrain the metal against a corresponding length ofthe member.

13. Apparatus according to claim 10, wherein a sensing device isprovided to sense entry of the metal into each gripping member.

14. Apparatus according to claim 8, wherein each gripping member isprovided with a pair of pinch rolls for driving out a leading end of alength of material which the clamping means have failed to arrest as thegripping members have received said material from a pass.

15. Apparatus according to claim 8, including carriages on which thegripping members are mounted for movement towards and away from the passunder the action of fluid pressure.

16. Apparatus according to claim 15, wherein the carriages are alsomounted for lateral movement.

17. Apparatus according to claim 8, wherein the gripping members aremounted for rotational movement about a longitudinal axis thereof.

18. Apparatus according to claim 8, wherein a load sensitive device isprovided to sense when a pair of rolls ceases to be under loadconsequent upon the metal having left that pair of rolls.

19. Apparatus according to claim 8, including two pairs of rolls anddriving means therefore for feeding metal between either pair of rollsin the direction of the other, at least one roll of each pair of rollsbeing retractable from an operative position to an inoperative position,the gripping members being mounted to extend through the gap between theadjacent inoperative pair of rolls to a forward position near the biteof the other pair of rolls.

20. Apparatus according to claim 19, wherein means are provided foreffecting vertical adjustments of the gripping members betweensuccessive rolling operations to compensate for the pass line betweenone pair of rolls being higher than the pass line between the other pairof rolls.

21. Apparatus according to claim 19, wherein abutments are provided todetermine the operative positions of the retractable rolls.

22. Apparatus according to claim 19, including screw means associatedwith a nonretractable roll of each pair of rolls for determining the gapbetween the rolls when the retractable roll is in its operativeposition.

1. A method of rolling metal, comprising gripping a first end portion ofthe metal for movement relative to a pass between rolls, entering thegripped metal into the pass by a first reciprocable gripping member forthe metal when the gripping member is moved toward the pass from arearward position, receiving the first end portion of the metal at theother side of the pass in a second gripping member mounted on said otherside for reciprocating movement towards and away from the pass, movingthe metal lengthwise in the direction of rolling relative to thegripping members until its other end portion is received in the secondgripping member, gripping said other end portion in the second grippingmember, and reentering said gripped other end portion between the rollsby movement of the second gripping member back towards the rolls forreception of said metal at the first mentioned side of the pass by thefirst gripping member.
 2. The method according to claim 1, characterizedby moving the end portion of the metal laterally by the gripping membersby the action of flUid operated means, when, prior to being entered intothe bite of a pair of rolls having a plurality of passes spaced fromeach other, the metal is aligned with the required one of said passes.3. The method according to claim 1, characterized by rotating thegripping members by the action of fluid operated turning means.
 4. Themethod according to claim 1, characterized by rotating a first pair anda second pair of rolls in opposite directions so that each is able tofeed said metal towards and away from the pass of the other, retractingat least one roll of the second pair to an inoperative position, movingthe second gripping member to a forward position in a gap between thesecond pair of rolls and alternately receiving from and entering intothe bite of the first pair of rolls an end portion of the metal, movingthe second gripping member to its rearward position clear of the secondpair of rolls, returning the retracted roll of the second pair to itsoperative position, retracting at least one roll of the first pair to aninoperative position, and moving the first gripping member to itsforward position in the gap between the first pair of rolls toalternately receive from and enter into the bite of the second pair theother end portion of the metal.
 5. The method according to claim 4,characterized by vertically adjusting the gripping members betweensuccessive rolling operations to compensate for the pass line betweenone pair of rolls being higher than the pass line between the other pairof rolls.
 6. The method according to claim 4, characterized byadjusting, while metal is passing through the pass of one pair of rolls,the position of a nonretractable roll of the other pair to determine thewidth of the roll gap of that other pair when its retractable roll hasbeen returned to its operative position.
 7. The method according toclaim 4, characterized by the movement of the gripping members and theretraction of the retractable rolls from and their return to theiroperative positions and the adjustment of the nonretractable rolls areall effected automatically.
 8. Rolling mill apparatus including at leasttwo rolls mounted to form at least one pass, a first gripping member anda second gripping member mounted on opposite sides of the pass forreciprocating movement towards and away therefrom, clamping means foreach gripping member adapted to releasably clamp metal in said grippingmembers alternately, and means for moving at least one of said grippingmembers independently of the other gripping member, said one of saidgripping members being adapted upon movement thereof to enter an endportion of metal into the pass and subsequently to receive near the passan end portion of metal travelling therefrom.
 9. Apparatus according toclaim 8, wherein each gripping member includes a tube for receiving themetal.
 10. Apparatus according to claim 8, wherein each clamping meansalso includes includes a lever.
 11. Apparatus according to claim 10,wherein each clamping means also includes a fluid pressure operatedpiston and cylinder arrangement for operating the lever.
 12. Apparatusaccording to claim 10, wherein the lever has an elongate part whichbears against metal adapted to be gripped by the associated grippingmember to constrain the metal against a corresponding length of themember.
 13. Apparatus according to claim 10, wherein a sensing device isprovided to sense entry of the metal into each gripping member. 14.Apparatus according to claim 8, wherein each gripping member is providedwith a pair of pinch rolls for driving out a leading end of a length ofmaterial which the clamping means have failed to arrest as the grippingmembers have received said material from a pass.
 15. Apparatus accordingto claim 8, including carriages on which the gripping members aremounted for movement towards and away from the pass under the action offluid pressure.
 16. Apparatus according to claim 15, wherein thecarriages are also mounted For lateral movement.
 17. Apparatus accordingto claim 8, wherein the gripping members are mounted for rotationalmovement about a longitudinal axis thereof.
 18. Apparatus according toclaim 8, wherein a load sensitive device is provided to sense when apair of rolls ceases to be under load consequent upon the metal havingleft that pair of rolls.
 19. Apparatus according to claim 8, includingtwo pairs of rolls and driving means therefore for feeding metal betweeneither pair of rolls in the direction of the other, at least one roll ofeach pair of rolls being retractable from an operative position to aninoperative position, the gripping members being mounted to extendthrough the gap between the adjacent inoperative pair of rolls to aforward position near the bite of the other pair of rolls.
 20. Apparatusaccording to claim 19, wherein means are provided for effecting verticaladjustments of the gripping members between successive rollingoperations to compensate for the pass line between one pair of rollsbeing higher than the pass line between the other pair of rolls. 21.Apparatus according to claim 19, wherein abutments are provided todetermine the operative positions of the retractable rolls. 22.Apparatus according to claim 19, including screw means associated with anonretractable roll of each pair of rolls for determining the gapbetween the rolls when the retractable roll is in its operativeposition.